1. Field
The exemplary embodiments relate coupling a substrate carrier to a load port and to purging the substrate carrier.
2. Brief Description of Related Developments
Current substrate carriers such as, for example, front opening unified pods (FOUPs) for carrying semiconductor substrates are manufactured from polymer materials like polycarbonate, polyethylenes and the like. These materials have a molecular structure which is larger than the molecule size of, for example, inert gases such as nitrogen or argon. For this reason the carrier material may not be sufficient to contain the inert gas which will diffuse through the carrier shell until all of the gas is lost. Denser materials with a molecular structure smaller than the molecule size of the gas may be used but denser materials may add undesired weight to the carriers. The gases are used during substrate processing to control the environment local to the substrates which may have materials deposited on them that are susceptible to moisture or oxygen. Current gas purging systems rely on storage nests that are plumbed to a house gas supply and continuously input gas into the carrier to compensate for leaks. Separate gas containers that travel along with the substrate carriers may also be known.
Also, conventional substrate carriers are mechanically coupled to the loadport via features on the bottom surface of carrier for registration to or alignment with the tool. For front opening carriers, the door, which is opened to access the substrates, is located on one side of the carrier and is perpendicular to the bottom surface. The door locating and latching features mate with corresponding loadport features. This forms two planes on the substrate carrier which are to be aligned with respect to the mating loadport planes. This negatively impacts the quality of the interface when carriers are not in tolerance or a loadport is not properly adjusted. In addition, the cost of producing each part can be higher due to complications maintaining the relationships between the two planes. An example of a conventional substrate carrier can be found in U.S. Pat. No. 5,895,191 which discloses an angled sealing surface that creates a wedge shaped door that can be removed with a single vertical axis of motion, and the carrier relies on the bottom surface of the carrier for carrier registration.
It would be advantageous to have a gas purging system that is localized to the carrier and a load port coupling that reduces the degrees of freedom to register the carrier to a tool and open the door for substrate access.